Method for the production of monoalkylbenzenes



Nov. 11, 1969 H. A. SORGENTI 3,478,118

METHOD FOR THE PRODUCTION OF MONOALKYLBENZENES Filed May 8, 1 968 E |.o 2 l 0.8 U 5 0e 5i- 0 1: 0.4 Z 02 n O 20 4O 6O 80 I00 ACTIVITY TEST CONVERS|ON,WT.%

INVENTOR.

HAROLD A .SORGENTI.

ATTORNEY United States Patent 3,478,118 METHOD FOR THE PRODUCTION OF MONOALKYLBENZENES Harold A. Sorgenti, Drexel Hill, Pa., assignor to Atlantic Richfield Company, Philadelphia, Pa., a corporation of Pennsylvania Filed May 8, 1968, Ser. No. 727,415 Int. Cl. C07c 3/56 US. Cl. 260-671 5 Claims ABSTRACT OF THE DISCLOSURE Production of monoalkylbenzenes from a chloroparafiin fraction having a high ratio of polychloroparaffins to monochloroparafiins by utilizing an aluminum chloride catalyst of controlled severity.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to a method for utilizing a chloroparaffin fraction having a higher than normal content of polychlorides to alkylate benzene to monoalkylben zenes by the use of an aluminum chloride catalyst of controlled severity.

PRIOR ART The alkylation of benzene with chloroparafiins to produce detergent alkylate has been practiced for a great number of years. Heretofore, it has been thought to be necessary to have a high ratio of monochloroparaflins to polychloroparaffins since the polychloroparaffins convert to heavy products and thus represent a yield loss, or to indans or tetralins or both which are undesirable as components of the heart cut detergent alkylate. For example in an article by G. C. Feighner The Manufacture of Detergent Alkylate, The I. Am. Oil Chem. Soc., Vol. 35, pp. 520-522 (1958) it is shown that paratfin dichlorides produce diphenyl alkanes and in British Patent No. 681,211 it is disclosed that if high conversions are employed in the chlorination of the paraffins the yield of monoalkylbenzenes is low, accordingly, the process was limited to 0.2 gram atom of chlorine per mole of hydrocarbon. Thus, in order to minimize polychloroparafiin production in the chlorination step of the process according to prior art processes the chlorination was carried out at low chlorination conversions per pass. As a result, the size of the plant required was increased by the high recycle ratio. The present invention differs from the prior art in that chloroparafiins having a relatively high polychloride content can be employed to produce the monoalkylbenzenes thus reducing the size of the plant required and the operating costs.

SUMMARY OF THE INVENTION In accordance with the instant invention, monoalkylbenzenes are produced by the alkylation of benzene with 3,478,118 Patented Nov. 11, 1969 ice a mixture of monochloroparafiins and polychloroparaffins wherein the ratio of polychloroparaflins to monochloroparaffins is higher than normally employed in alkylation processes. This is accomplished by the use of aluminum chloride catalyst of controlled severity.

In the invention is further described by means of the drawings wherein FIGURE I shows the catalyst activity factor plotted against the activity test conversion.

It is an object of this invention to provide a method for utilizing a mixture of monochloroparaffins and poly chloroparaflins having an abnormally high ratio of polychloroparaifins to monochloropar-aflins to alkylate benzene to monoalkylbenzenes.

It is another object of this invention to provide a method for the production of monoalkylbenzenes by alkylating benzene with a mixture of monochloroparaflins and polychloroparaflins of abnormally high polychloroparaflin content by the use of an aluminum chloride catalyst of controlled severity.

Other objects of this invention will be apparent from the description of the preferred embodiments and from the claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Although the alkyl group attached to the benzene ring of the monoalkylbenzenes of this invention can contain from 8 to 18 carbon atoms, preferably it contains from 10 to 16 carbon atoms since this is more suitable for commercial detergents. A particularly preferred range is that wherein the alkyl group has about a four carbon number spread with the average being approximately 12 carbon atoms.

In producing these monoalkylated benzenes it is necessary to employ alkyl chlorides having the corresponding number of carbon atoms to alkylate the benzene. It is necessary that the alkyl group be straight chain in order that the finished detergent will be biodegradable. Consequently, the alkyl chlorides are prepared. by chlorinating straight chain paraflin hydrocarbons in the desired carbon number range. Heretofore, as has been pointed out, the chlorination was carried out in a manner to produce predominantly the paraflin monochlorides. In doing this, low conversions were utilized which required high recycle which in turn added to the size of the plant and increased operating costs. In general, the chlorination was carried out so that only from 10 to 35 percent conversion of parafiins to chloroparaffin was obtained and under these conditions the monochlorides were of the order of 93 to 81 percent, respectively, of the chlorinated product. By utilizing the method of the present invention, however, the chlorination may be carried out so that the monochloroparaffin content of the chlorinated product can be as low as percent or lower with the remaining 25 percent or more being polychlorides. As used herein the term polychlorides or polychloroparaffins" refers to parafiin chlorides having 2 or more chlorine atoms per molecule. In general, the method of this invention is particularly applicable to the conversion of chlorinated paraffin fractions wherein the monochloroparafiin content of the chlorinated paraffins is lower than normal, i.e. less than about 80 percent and the polychloroparaflin content of the chlorinated paraffins is higher than normal, i.e. higher than about 20 weight percent.

As in the present alkylation methods the chlorinated paraffin admixed with unchlorinated paraflin is utilized to alkylate the benzene and after alkylation the unchlorinated parafiin is separated from the alkylated benzene and recycled to the chlorination step. Since the limitation on low conversion in the chlorinating step is removed by the method of this invention, the quantity of parafiin which must be recycled is lower and thus the size of the plant and operating costs are reduced.

The method of this invention is carried out under conventional alkylation reaction conditions, i.e. at temperatures ranging from about 135 F. to 250 F. with a molar excess of the benzene over the alkyl chloride (chloroparafiin). In general, a volume ratio of benzene to chloroparaflin is in the range of from about 1:1 to :1, with the conventional ratio of 5:1 being completely suitable.

As in conventional alkylation processes the catalyst employed in this invention is a conventional liquid aluminum chloride complex, for example, the complex of aluminum chloride with the alkylated benzenes produced or with the aromatic hydrocarbon, for example, benzene. The aluminum chloride consists of from about 35 weight percent to 50 weight percent of the complex with the remainder being the hydrocarbon. In general, the average aluminum chloride content of the complex is about 40 Weight percent. The activity of the catalyst system can be increased by the addition of fresh aluminum chloride to the system or by the addition of finely divided metallic aluminum which reacts with the hydrogen chloride produced in the process to form aluminum chloride in situ. The activity of the catalyst system can also be decreased by adding other complexing agents such as nitromethane which forms a more stable complex and thus lowers the catalyst activity or by the addition of water which deactivates the catalyst. The catalyst ordinarily is deactivated during use by the tars and heavy products formed during the reaction. Accordingly, by adding fresh aluminum chloride (or metallic aluminum as has been described) the level of the activity of the catalyst can be controlled.

The aluminum chloride content of the catalyst which may vary as has been described from about 35 weight percent to 50 weight percent of the liquid catalyst system is not a suflicient criterion of catalyst activity since deactivation may have occurred through use or by the deliberate addition of a deactivating material. Since catalyst activity is an important factor in controlling catalyst severity and since the control of catalyst severity is a critical factor of the present invention the control of catalyst activity is also an important factor in the present invention.

A test method has been devised therefore to determine accurately catalyst activity.

In carrying out the test to determine the activity of an aluminum chloride catalyst, 50 ml. of a mixture of benzene, l-chlorododecane, and dodecane is dried over magnesium sulfate and charged to a flask. The mixture is heated to reaction temperature (200 F.) and 1 ml. of the liquid aluminum chloride catalyst complex is added. The reaction mixture has the composition:

Volume ratio Benzene/ l-chlorododecane 5/ l Dodecane/ l-chlorododecane 9/ 1 Catalyst complex/ l-chlorododecane 0.3/1

One minute after the addition of the liquid aluminum chloride complex to the reaction mixture, a sample of the reaction mixture is taken and analyzed by gas chromatography to determine the quantity of l-chlorododec- (Equation 1) where X is the fraction of primary chloride converted; C is the aluminum chloride concentration in moles per liter; C is the benzene concentration in moles per liter; t is the reaction time in minutes; k is the catalyst activity factor; k is the reaction rate constant for primary chloride (a function of temperature); and where the value of kp at three representative temperatures is 200 at 250 F.; 32 at 200 F. and 12 at F., the units of k being (moles/1iter)'- (minutes)* Since the plot of the lnk versus l/T, Where T is the absolute temperature, is a straight line, the value of k at any temperature may be found from the representative values set forth above.

Since all the other variables which affect the rate of reaction, i.e. time, temperature, catalyst concentration and benzene concentration are held constant for the test the only variables in the test are conversion and catalyst activity. The catalyst activity factor ranges between 0 and 1.0. The k was arbitrarily assigned a value of 1.0 for a conversion fraction X of 0.99 at test conditions and a value of 0 for a conversion of 0. The values of the activity factor between these limits were calculated for their corresponding conversions. The resulting curve is shown in FIGURE I of the drawings. It will be seen from this figure that the activity factor of any catalyst may be read from the curve simply by measuring the quantity of 1- chlorododecane converted at test conditions in one minute. It should be noted that all concentrations in Equation 1 which are in moles per liter refer to moles per liter of the entire reaction mixture.

In addition to catalyst activity, catalyst concentration is the second important factor in determining catalyst severity in the alkylation reaction. Catalyst severity therefore is defined as the product obtained when k the catalyst activity factor is multiplied by the concentration of aluminum chloride in moles per liter of reaction mixture, i.e. k XC In order to attain the objectives of this invention, i.e. the conversion of polychloroparafiins to monoalkylbenzenes, the catalyst severity (k XC must be in the range of from 0.05 to 0.5. A somewhat more preferred range is from 0.1 to 0.4.

The comparative data which are set forth in the following example are provided for the purpose of demonstrating specific embodiments of the invention and to show the necessity of utilizing a critical catalyst severity. The data set forth in this example, however, should not be construed as limiting the invention thereto.

EXAMPLE Six batch alkylation runs were carried out wherein a mixture of monochloroparafiins and polychloroparafiins having 12 carbon atoms in the molecule with only a small amount (approximately 5 percent) of material of slightly higher and lower carbon number content was employed to alkylate benzene. In runs 1, 2 and 3 a low temperature, i.e. 135 F. was employed While in runs 4, 5 and 6 high temperatures, i.e. F. to 200 F. were employed.

In the table the feed stock analysis, i.e. the amount of straight chain C monochloroparafiins and polychloroparaifins, the reaction conditions, the catalyst activity factor and catalyst severity (activityxconcentration) are 5 shown together with the results obtained including the analysis of the product.

savings in reactor size and throughput as Well as operating costs are obvious.

Run No.

Feedstock:

Monoehloroparatlins 89. 4 70. 3 70. 3 89. 4 70. 3 70. 3

lolychloroparalfius 23. 2 23. 2 10. 6 23. 2 23. 2

Parallin 6. 5 6. 5 6. 5 6. 5 Conditions:

Temperature, F 135 135 135 200 180 180 Pressure, p.s.i.g Atni. Atrn. Atnr. Atrn. Atm. Atm.

Benzene/chloride v./v 5/1 5/1 5/1 5/1 5/1 5/1 Slurry/chloride v./v 1.8 0.6 1. 8 0.6 1. 8 1. 8 Catalyst activity factor k A 0. 031 0. 031 0. 84 O. 031 0. 031 0. 84 Catalyst severity kn C 0. 0115 0. 0037 0. 31 0. 0037 0. 0115 0. 31 Conversion 98. 7 9 2 99. 7 100 98. 5 99. 7 Yield, lbs. heavy alkylate lbs. heart out alkylate O. 079 0. 127 0. 054 0.12 0. 14 0.068 Wt. percent rnonoalkylbenzenes in heart out product 94. 5 93.8 91. 4 93.0 92. 90. 2

1 Boiling range above 620 F.

2 Boiling range 520 F.620 F.

The polychloroparaffin to monochloroparaflin ratio in As many possible embodiments can be made of this runs 1 and 4 is conventional, i.e. that which is obtained 20 invention without departing from the broad scope thereof,

when the chlorination reaction is carried out to about 10 percent conversion so that a monochloroparafiin content of about 90 weight percent in the chlorinated prod not is obtained. In runs 2, 3, and 6 the polychloride content of the chlorinated product was between 2 and 2 /2 times the polychloride content in conventional chlorination. Such a polychloride content is obtained when a 40 to 50 percent conversion level (instead of a percent conversion level) is carried out in the paraffin chlorination step. It will be seen in comparing run 1 with run 3 and run 4 with run 6 that if catalyst severities in the range set forth as being critical herein are utilized, i.e. from 0.05 to 0.5, the reaction conversion level is maintained while the yield ratio of heavy alkylate to heart out alkylate is actually decreased. Heretofore, polychloroparaffins were converted only to undesirable byproducts (diphenyl alkanes, etc.) and it was assumed that these were the only products that could be made from them, these data show, however, that by the process of this invention the contrary is true, i.e. that they can be converted to monoalkylbenzenes. Runs 2 and 5 when compared respectively with runs 3 and 6 show the necessity of utilizing high severities in order to obtain the desired results. Moreover, the analysis of the product shows that in addition to maintaining conversion and obtaining a lower yield of heavy alkylate substantially the same purity of heart cut alkylate is obtained when a high polychloride content feed is treated in the presence of a high severity catalyst level.

The importance of this invention is readily apparent when the advantage in the chlorination step of utilizing a to percent conversion instead of a 10 percent conversion is considered. When a 10 percent conversion level in the chlorination step is used the recycle ratio of parafiins recycled is 9:1, whereas at the 40 to 50 percent conversion level the recycle ratio is only 2:1. The

it is to be understood that all matter herein set forth is to be interpreted as illustrative and not as unduly limiting the invention.

I claim:

1. The method for alkylating benzene with a mixture of monochloroparaffins and polychloroparafiins wherein the polychloroparafiin content of the chlorinated parafiins is at least 20 Weight percent which comprises reacting said mixture of monochloroparaffins and polychloroparaffins with benzene under alkylation conditions utilizing an aluminum chloride catalyst with the catalyst severity being in the range of from 0.05 to 0.5.

2. The method according to claim 1 wherein said chlorinated paraflins contain from 8 to 19 carbon atoms.

3. The method according to claim 1 wherein said chlorinated paratfins contain from about 10 to about 16 carbon atoms with an average of about 12 carbon atoms.

4. The method according to claim 1 wherein said chlorinated paraffins contain an average of about 12 carbon atoms with about a 4 carbon number range.

5. The method according to claim 1 wherein the chlorinated paraflins are obtained by chlorinating a parafiin fraction to more than 35 weight percent conversion.

References Cited UNITED STATES PATENTS 2,756,265 7/1956 Hollyday 260671 3,231,517 1/1966 Bloch et al. 26067l X 3,303,230 2/1967 McMinn 260-671 3,337,613 8/1967 Luberoff 260-671 X 3,342,888 9/1967 De Witt et al 260---671 DELBERT E. GANTZ, Primary Examiner C. R. DAVIS, Assistant Examiner UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,478,118 November 11, 1969 Harold A. Sorgenti It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line 34, "8 to 19 carbon atoms" should read 8 to 18 carbon atoms Signed and sealed this 3rd day of March 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr. E. JR.

Attesting Officer Commissioner of Patents 

